Models may be used to simulate physical systems. For example, a graphical model may be used to represent a complex control system for a plant. The graphical model may include entities, such as blocks, that reference executable code for performing operations of the control system when the graphical model executes. The blocks can vary in type and/or number and may be connected together to build large, complex models (e.g., models including hundreds or more interconnected blocks).
At times, a user may wish to observe how a portion of the model is operating. One technique for observing model operation involves using a scope display in the model. The scope display allows the user to observe moving data with respect to an x and y-axis. For example, the y-axis may indicate the amplitude of a signal and the x-axis may indicate time or frequency for the signal.
Users may set limits for the x and y axes on the scope based on expected characteristics of the signal. Often a user's guess with respect to signal characteristics may be wrong, and the signal amplitude my exceed an upper or lower limit of the display. At other times, the user may set upper/lower limits that are much larger than the signal amplitude thus making the signal difficult to observe. Conventional scopes may autoscale as soon as an out-of-range sample is detected. For example, when the amplitude of a sample exceeds the upper limit of the scope, the scope rescales so that the sample can be seen. If a subsequent sample exceeds the rescaled upper limit, the scope rescales again. When signals do not exceed the upper limit, the scope may rescale again to make the displayed signal occupy the full display area of the scope.
At times the scope may rescale so frequently that a user becomes frustrated with the autoscaling capability of the scope. For example, the user may become frustrated because the display rescales so frequently that the user does not have time to interpret the displayed signal before the signal rescales again. In these situations, a user may place the scope into a manual mode which may result in signal data not being displayed when a sample is out of range, or signal data being displayed without adequate resolution when the signal is small with respect to the available display area of the scope.
The shortcomings associated with conventional autoscaling techniques for use with moving data may interfere with a user's ability to efficiently assess whether a model is performing in an expected manner.